A U.S.-backed Syrian rebel group has established a secret prison camp for former Islamic State militants and their families, the BBC News reported Wednesday. The camp is located in a village in Northern Syria, where the operation to crush the Islamic State has reportedly caused a number of civilians and fighters to flee its territory.

The internment camp, created by Jaysh al-Tahrir, is reported to host up to 300 defectors and captured combatants of the Islamic State, including a number of Europeans. The goal of the camp is to rehabilitate those who lived and fought under the Islamic State, according to Jaysh al-Tahrir commander Mohammad al-Ghabi. Ghabi claims that the militants, who hail from France, the Netherlands and Poland, as well as Middle Eastern and Asian countries, have been allowed to contact their native embassies.

Those who did not wish to return to their home nations or were suspected of committing crimes would stand trial in a Sharia court and be subject to Islamic law. Ghabi confirmed that some could be executed if found guilty.

Jaysh al-Tahrir was formed by the Free Syrian Army in February. It was vetted by the CIA and was intended as a moderate buffer to more radical groups such as the Nusra Front. It has received significant tactical support from the U.S. and since August has been fighting alongside Turkish-backed Islamic groups in Turkey's push against the Islamic State known as Operation Euphrates Shield, the Long War Journal reports.

Jaysh al-Tahrir has both clashed with and fought alongside more radical groups throughout the conflict. In July, the Nusra Front kidnapped Ghabi along with several of his aides and arrested 40 fighters. Ghabi was later released after reaching a deal to avoid mutual aggression.